Is this wing already sheeted? or is it a core? I have repaired some serious fractures in both and I have come to find that it is best to completely break the fracture and epoxy it back on. This is the only way to get 100% bond. Styro breaks with a very irregular fracture allowing a good glue surface. Alignment dowels can be used also. I have glued horizontal stabs back on using this method that were cracked at the fuse side. It ended up being stronger than the before fractured piece. In my opinion polyurathane glue is not the best way to go in this situation, epoxy!! I would break it loose, completely saturate the break with 30minute epoxy and mate the surfaces back together. If epoxy ozzes from the break its 100%. If the core is not sheeted Do the same but alphetic glue will work fine..This is from my experience which does work..walt